Forms an air-tight seal on all smooth rims, including glass, plastic, stainless steel and melamine. Retains steam to keep your coffee, tea and other beverages hot for a longer period of time. Insulates to keep cocktails and other beverages cold for a longer period of time. Covers the surface of the glass to prevent insects and other debris from entering. Creates SMILES for you and your guests with its contemporary, nature-inspired design.